Experimental Study Of Surfactant Flooding In Reducing Injecting Pressure And EOR For Low-permeability Reservoir

So far, the reserve of low permeability reservoirs has been large in petroleum resources in our country. But the physical properties of low permeability reservoirs are usually very poor, different from common reservoirs, and high flooding pressure and low recovery are commonly found in low permeability reservoirs. Furthermore, the common fracture and acid treatment cause great damage to the formation and the effective time is short, but surfactant flooding in high permeability reservoirs has achieved good results. So the mechanism study of surfactant flooding in lowering injection pressure and improving oil recovery is significant to the development of low permeability reservoirs. This paper first studied the selection principle and the performance property evaluation method of the surfactant used for reducing injecting pressure and EOR efficiency. The concentrations of surfactant, salinity and temperature on interfacial tension behaviors are investigated. Carried out chemical flooding to reduce injecting pressure and improve EOR efficiency in different permeability cores displacement tests, evaluated the influence of surfactant flooding in low permeability reservoirs. Also, the IFT of water and oil, surfactant slug size, injection rate and injection opportunity on reducing injecting pressure and improving EOR efficiency are investigated. Research indicates that surfactant flooding can decrease the injection pressure of low permeability cores, improve the two phase flow condition, increase the permeability of both phases, widen two phase flow region and improve the EOR efficiency. Detection results exhibit that with the decrease of the IFT of oil and water and the increase of the surfactant slug size, the lowering injection pressure effectiveness rises, which decreases with the injection rate. The earlier the surfactant slug injects the better flooding effectiveness. There is a best parameter combination in surfactant flooding. The work in this paper will give a guide for surfactant flooding in low permeability reservoirs.